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Added icestick rs232 demo

This commit is contained in:
Clifford Wolf 2016-12-30 14:29:44 +01:00
parent 47d28bff12
commit cd0e6cfa8e
3 changed files with 65 additions and 0 deletions
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4
examples/icestick/.gitignore vendored
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@ -2,3 +2,7 @@ example.bin
example.blif
example.asc
example.rpt
rs232demo.bin
rs232demo.blif
rs232demo.asc
rs232demo.rpt

2
examples/icestick/icestick.pcf
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@ -1,3 +1,5 @@
set_io --warn-no-port RX 9
set_io --warn-no-port TX 8
set_io LED1 99
set_io LED2 98
set_io LED3 97

59
examples/icestick/rs232demo.v Normal file
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@ -0,0 +1,59 @@
module top (
input clk,
input RX,
output TX,
output reg LED1,
output reg LED2,
output reg LED3,
output reg LED4,
output reg LED5
);
parameter integer BAUD_RATE = 9600;
parameter integer CLOCK_FREQ_HZ = 12000000;
localparam integer HALF_PERIOD = CLOCK_FREQ_HZ / (2 * BAUD_RATE);
reg [9:0] buffer;
reg buffer_valid;
reg [$clog2(3*HALF_PERIOD):0] cycle_cnt;
reg [3:0] bit_cnt = 0;
reg [0:0] state = 0;
always @(posedge clk) begin
buffer_valid <= 0;
case (state)
0: begin
if (!RX) begin
cycle_cnt <= HALF_PERIOD;
bit_cnt <= 0;
state <= 1;
end
end
1: begin
if (cycle_cnt == 2*HALF_PERIOD) begin
cycle_cnt <= 0;
buffer[bit_cnt] <= RX;
bit_cnt <= bit_cnt + 1;
if (bit_cnt == 9) begin
buffer_valid <= 1;
state <= 0;
end
end else begin
cycle_cnt <= cycle_cnt + 1;
end
end
endcase
end
always @(posedge clk) begin
if (buffer_valid) begin
if (buffer[8:1] == "1") LED1 <= !LED1;
if (buffer[8:1] == "2") LED2 <= !LED2;
if (buffer[8:1] == "3") LED3 <= !LED3;
if (buffer[8:1] == "4") LED4 <= !LED4;
if (buffer[8:1] == "5") LED5 <= !LED5;
end
end
assign TX = RX;
endmodule